循环荷载作用下广西红黏土动力特性试验研究

Experimental Study on Dynamic Properties of Red Clay in Guangxi under Cyclic Loading

摘要:

针对广西上林县原状红黏土开展一系列循环加载动三轴试验,分析天然含水率、围压与固结应力比等对红黏土动力特性,包话动应力-动应变关系、动弹性模量以及阻尼比等的影响来研究循环荷载作用下红黏土的动力特性。试验结果表明:广西原状红黏土动应力-动应变关系曲线接近双曲线;由于初始剪应力的影响,达到相同的动应变,在均压固结下所需的动应力比在偏压固结下所需动应力要小;动弹性模量随着动应变的增加而减小,且减小幅度随应变增加逐渐减小,初始应力状态对动弹性模量的影响最为显著;固结应力比、围压、含水率和振动次数等对阻尼比均有影响,综合反映在阻尼比随动应变增加而减小,阻尼比离散性较大,取值范围在0.05~0.20之间。利用 Konder双曲线模型对试验数据进行拟合,得到相关参数,可为广西地区原状红黏土动力特性设计和数值计算提供一定的理论和参数支持。

Abstract:

In order to study the dynamic properties of red clay under cyclic loading conditions,a series of cyclic triaxial tests are carried out on undisturbed red clay obtained from Shanglin county,Guangxi.The impacts of water content,confining pressure,and consolidation stress ratio on the dynamic properties of red clay such as the dynamic stress-strain relationship,dynamic elastic modulus,and damping ratio are analyzed.It is indicated from the test results that the stress-strain curve of red clay from Guangxi is close to a hypobolic style;due to the effects of the initial shear stress,a higher dynamic stress is needed to obtain the same strain under anisotropic consolidation as under isotropic consolidation;the dynamic modulus decreases as the dynamic strain increases;the decrease in amplitude decreases with the increase of the dynamic strain;and the initial stress state has the most significant impact on the dynamic elastic modulus.The damping ratio is affected by the consolidation stress ratio,confining pressure,and water content of red clay from Guangxi,and it increases as the dynamic strain increases,with its value distributed between 0.1 and 0.2.The damping ratio data has a high discreteness.Based on the hyperbolic model by Konder,test data are fitted,and relevant parameters are obtained.This research could be a reference for further design of dynamic properties and numerical calculation,and it also provides relevant parameters.